Răspuns :
a)
935 - a + 72 x 12 = 1500
935 - a + 864 = 1 500
935 - a = 1 500 - 864
935 - a = 636
a = 935 - 636
a = 299
b)
170 - ( 18 + 2 x a ) : 5 = 10
( 18 + 2 x a ) : 5 = 170 - 10
( 18 + 2 x a ) : 5 = 160
18 + 2 x a = 160 x 5
18 + 2 x a = 800
2 x a = 800 - 18
2 x a = 782
a = 782 : 2
a = 391
935 - a + 72 x 12 = 1500
935 - a + 864 = 1 500
935 - a = 1 500 - 864
935 - a = 636
a = 935 - 636
a = 299
b)
170 - ( 18 + 2 x a ) : 5 = 10
( 18 + 2 x a ) : 5 = 170 - 10
( 18 + 2 x a ) : 5 = 160
18 + 2 x a = 160 x 5
18 + 2 x a = 800
2 x a = 800 - 18
2 x a = 782
a = 782 : 2
a = 391
935 - a + 72 × 12 = 1500
935 - a + 864 = 1500
935 - a = 1500 - 864
935 - a = 636
935 - 636 = a
a = 299
170 - (18 + 2a ) : 5 = 10
(18 + 2a ) : 5 = 170 - 10
(18 + 2a ) : 5 = 160
18 + 2a = 160 × 5
18 + 2a = 800
2a = 782
a = 391
935 - a + 864 = 1500
935 - a = 1500 - 864
935 - a = 636
935 - 636 = a
a = 299
170 - (18 + 2a ) : 5 = 10
(18 + 2a ) : 5 = 170 - 10
(18 + 2a ) : 5 = 160
18 + 2a = 160 × 5
18 + 2a = 800
2a = 782
a = 391