Question

7 tens 5ones - 3 tens 3 ones=?

Answer 1

$7 \times 10 + 5 - 3 \times 10 - 3 = 75 - 33 = 42$

Answer 2

7 tens = 70
5 ones = 5
3 tens = 30
3 ones = 3
therefore,
(70+5)-(30+3) =75-33=43