Question

(12 + 8 + 20 -10) x 3 : (25 - 15)

Answer 1

(20+20-10) x3 : 10 =
(40-10) x3 :10 =
30 x3 :10 =
90 : 10 =
9

Answer 2

Solución

$(12 + 8 + 20 - 10) \times 3 \div (25 - 15)\\ 30 \times 3 \div (25 - 15) \\ 30 \times 3 \div 10 \\ 9$