100сек больше. 1мин=60сек 60+30=90сек
1) (25 + 20) * 2 = 45 * 2 = 90 см длина скатерти по краям
2) 1 метр = 100 см
3) 100 см > 90 см - хватит ленты в 1 м еще останется 10 см
1. х/2 - х/3 -х/6 = 3х/6 -2х/6 -х/6 = 0
2, 5/9z - 1 3/4 z +17/18 = 20/36 z - 1 27/36 +17/18 = - 1 7/36 z + 17/18
3. 5у - 8х -7х = 5у -15х
4, 2,5х -3у -3х + у = -0,5х -2у
5. 0,2у +3у -1,5у = 1,7у
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