1) 4/15 + 1/2 = 8/30 + 15/30 = 23/30
2) 8/9 + 1/6 = 16/18 + 3/18 = 19/18 = 1 1/18
3) 4/7 - 3/70 = 40/70 - 3/70 = 37/70
4) 9/14 - 2/7 = 9/14 - 4/14 = 5/14
1,75+1 1/42=1 75/100+1 1/42=1 1575/2100+1 50/2100=2 1625/2100=2 65/84
4(X-16)-(8-X)=10(X+1)-2(15+8X) 4x-64 -8+x=10x+10-30-16x 4x+x-10x +16x=10-30+64 11x=44 x=4