Number of oranges is (2a + 2)
Half the number of oranges is 1/2(2a + 2)
Half the number of apples is 1/2a
The difference between half the number of oranges and half the number of apples equals 4 looks like this:
1/2(2a + 2) - 1/2a = 4
Now solve.
1/2(2a + 2) - 1/2a = 4 (multiply 1/2 by what's inside the parenthesis)
1a + 1 - 1/2a = 4
1a + 1 -1 - 1/2a = 4 - 1
1a - 1/2a = 3
1/2a = 3
1/2a ÷ 1/2 = 3 ÷ 1/2
a = 6
He has 6 apples.
Substitute 6 into the equation for the number of oranges.
2a + 2
2(6) + 2 = 14
He has 14 oranges.
Check your work.
The difference between half the number of oranges (7) and half the number of apples (3) does indeed equal 4.
Therefore, the equation has one solution.