Question

Put the same number in each box to make the

calculation correct.
140 + 10 - ___ = _____ - 30

Answer 1

Answer: 90

Explanation:

Let's use x as a placeholder to the number we are trying to find

`140+10-x=x-30`

Now we need to isolate x

Step 1) Simplify both sides

`140+10-x=x-30\\150-x=x-30`

Step 2) Add 30 to both sides

`150-x+30=x-30+30\\180-x=x`

Step 3) Add x to both sides

`180-x+x=x+x\\180=2x`

Step 4) Divide both sides by 2

`(180)/(2)=(2x)/(2) \\90=x`

Step 5) Sub our value into the original equation and solve

`140+10-x=x-30\\140+10-90=90-30\\150-90=60\\60=60`

Answer 2

The number would be 90

Explanation:

140 + 10 - 90 = 60

90 - 30 = 60

60 = 60