Question

There is a value of a such that subtracting a-4 from 4a+16 gives an answer of -25. What is that value of a?

Answer 1

Let's see what happens:

4a+16 - (a-4) = 3a + 20 = 25 => 3a = 5 => a = 5/3

Answer 2

If you subtract (a-4) from (4a+16), the new equation to work with would be 3a + 12. And if the difference of these two equations is 3a + 12, which would give an answer of -25, (pictured 3a + 12 = -25), by using algebra we could try a = -13/3 or a equals negative 13 over three. I hope this helps