Question

the sum of eight times a number and seven is twice the number

Answer 1

EXAMPLE:

`The sum of three times a number and seven is five times the number`

Lets call this "number" - x. We get,
`The sum of three times x and seven is five times x`

Three times x is: 3•x, or just 3x. So we get:
`The sum of 3x and seven is five times the number`

"Sum of A and B" is: A+B
And so is: "sum of 3x and seven" is: 3x+7 So we get:
`3x+7 is five times the number`

is, means equals, so we can now have:
`3x+7 = five times the number`

we said that "3 times the number" is 3•x or just 3x.
Same way would be: "5 times the number" - 5•x or just 5x. So we get:
`3x+7 =5x`

Answer 2

So in this example we have:
` The sum of three times a number and seven is five times the number `
---> 3x+7 =5x