7)
a ) a/(a+b) + b/ (a +b )= (a+b) / (a+b) = 1
b) a / (a+b+c) + b/ (a+b+c) + c / (a+b+c) = (a+b+c) / (a+b+c) = 1
8) a) 7/11 = 1/11 + 6/11
b) 5/9 = 1/9 + 4/9
c) 24/17 = 10/17 + 9/17 + 5/17
d) 6a/23 = 2a/23 + 4a/23
e) (2a + 5) / 5a= (a+1)/5 + (a+4)/5
f) (a+9) / (a+1) = (a+5) / (a+1) + 4 / (a+1)
9) 4 / 3 + 2 / 3 = 6 / 3 = 2