添上括号使下面的等式成立.

问题描述:

添上括号使下面的等式成立.
240 ÷ 4 + 20 - 2 = 8 90 - 30 ÷ 30 × 5 = 10
240 ÷ 40 + 20 × 2 = 52 90 - 30 ÷ 3 × 5 = 400

240 ÷ (4 + 20) - 2 = 8
(90 - 30) ÷ 30 × 5 = 10
(240 ÷ 40 + 20 ) × 2 = 52
(90 - 30 ÷ 3 )× 5 = 400