Question

I really need help with this

Answer 1

7

Explanation:

set up your two equations.

j + a = 20. equation 1

j = a + 6. equation 2

since you know that j = a + 6, you can substitute a + 6 into the place of j. this is because you want to isolate a in order to find out how many problems andy completed.

j + a = 20

a + 6 + a = 20

now solve.

2a + 6 = 20

2a = 14

a = 7

andy has completed 7 problems. if juana completed 6 more than andy, then she has completed 13. 13 + 7 = 20.

Answer 2

A+6+A = 20

A = 7

Explanation:

J = number of problems Juana completed

A = number of problems Andy completed

J+A=20

J = A + 6

Replace J with A+6 in the first equation

A+6+A = 20

2A +6 = 20

Subtract 6 from each side

2A +6-6 = 20-6

2A =14

Divide by 2

2A/2 = 14/2

A = 7