How are line drawing coordinates set in this js canvas code?

Question

JavaScript

I am learning from a book. There is an example of code for drawing lines on a canvas, in general, the code is clear except for one nuance in the loop:
"context.fillText(' cap:' + caps[j], 88 + j * 180, 45 + k * 120 )
...
context .lineTo(155 + j * 180, 20 + k * 120 )" .... I don't specifically understand what this expression 88 + j * 180
means in the fillText method and the same thing in the MoveTo and LineTo methods. Are these coordinates? and how are they counted? why through a multiplier? In general, there are more questions than answers (((I post the full code of the example below, I will be grateful for any help, I really want to figure it out.

<canvas id="mycanvas" width="535" height="360">Это элемент холст</canvas>

function O(i) {return typeof i == 'object' ? i : document.getElementById(i)}
      function S(i) {return O(i).style}

      canvas = O('mycanvas')
      context = canvas.getContext('2d')
      S(canvas).background = 'lightblue'
      context.strokeStyle 	= 'green'
      context.fillStyle 	= 'red'
      context.font 			= 'bold 13pt Courier'
      context.textBaseline = 'top'
      context.textAlign 	= 'center'
      context.lineWidth 	= 20
      caps						= [' butt', 'round', 'square']
      joins						= [' roud', ' bevel', ' miter']
      for (j = 0; j < 3; ++j)
      {
        for (k = 0; k < 3; ++k)
        {
          context.lineCap = caps[j]
          context.lineJoin = joins[k]
          context.fillText(' cap:' + caps[j], 88 + j * 150, 45 + k * 120)
          context.fillText(' join:' + joins[k], 88 + j * 180, 65 + k * 120)

          context.beginPath()
          context.moveTo(20 + j * 100, 100 + k * 100)
          context.lineTo(20 + j * 100, 20 + k * 100)
          context.lineTo(155 + j * 100, 20 + k * 100)
          context.lineTo(155 + j * 100, 100 + k * 100)
          context.stroke()
          context.closePath()
        }
      }

Answer 1

It's just more convenient to count in a cycle.

• 88 is some indent
  
• 100 is a step
  
• j - step number
  

for (let j = 0; j < 3; j++) {
  const x = 88 + j * 100; // умножение выполнится раньше сложения
  console.log(x); // 88, 188, 288
}