a)
0,2/(37/10) =x/30(2 2/3 +3,5)
2/37 =x/30(8/3 +35/10)
2/37 =x/30(80+105/30)
2/37 =x/185
x=2×185/37=10
b)
x/1,2=(2,5-1 2/3)² /(5/24)
10x/12=(25/10-5/3)² /(5/24)
5x/6=[(75-50)/30]² ×24/5
5x/6=(25/30)² ×24/5
5x/6=(5/6)² ×24/5
5x/6=25/36 ×24/5
5x/6=5/3 ×2/1
x/6=2/3
x=2×6/3=4
