Bruce bought two books. One book cost 4.00 more than three times the other together, two books cost him 72 find prices for the two books

The first book: 4 + 3x

The second book: x

Overall cost: $72

We can write it as an equation:

72 = 4 + 3x + x

72 = 4 + 4x / - 4 (both sides)

68 = 4x / : 4 (both sides)

x = 17

Now we can check it:

The first book: 4 + 3 * 17 = 4 + 51 = $55

The second book: $17

$55 + $17 = $72, so it's correct.