Question

180÷{10+2×[20-45÷(13-2×5)]}

Answer 1

180 ÷ {10 + 2 * [20 - 45 ÷ (13 - 2 * 5)]}
180 ÷ {10 + 2 * [20 - 45 ÷ (13 - 10)]}
180 ÷ {10 + 2 * [20 - 45 ÷ 3]}
180 ÷ {10 + 2 * [20 - 15]}
180 ÷ {10 + 2 * 5}
180 ÷ {10 + 10}
180 ÷ 20
9
Ok, that was a ton of work. Hope it helped :)
~Silver

Answer 2

180÷(10 +2(20 -45÷(13 -2*5)))
= 180÷(10 +2(20 -45÷(13 -10)))
= 180÷(10 +2(20 -45÷3))
= 180÷(10 +2(20 -15))
= 180÷(10 +2*5)
= 180÷(10 +10)
= 180÷20
= 9