In what year was her grandpa lopez twice as old as her dad? show how you know

So,

We are trying to figure out when Grandpa Lopez's age was twice that of Dad.

Let x represent the number of years before/after when G. Lopez's age was twice that of Dad.

66 + x = 2(37 + x)

Distribute.
66 + x = 74 + 2x

Subtract x from both sides.
66 = 74 + x

Subtract 74 from both sides.
-8 = x

So 8 years ago, G. Lopez was twice as old as Dad.  Let's check that.

66 - 8 = 58

37 = 8 = 29

29 * 2 = 58
58 = 58

It checks.

The amount used= 13.04- 1.9 = 11.14