Question

Justify the property:
1. If a/b = c/d, then b/a = d/c
2. If a/b = c/d, then a+b/b = c+d/d

Thanks! x

Answer 1

1. a/b = c/d
cross multiply, get
bc = ad
divided by ac on both sides, get
bc/ac = ad/ac (cancel out the similar terms)
b/a = d/c

Answer 2

2. If a/b = c/d
add by 1 on both sides, get
a/b + 1 = c/d + 1
a/b + b/b = c/d + d/d
(a+b)/b = (c+d)/d

Answer 3

Thanks so much! Is there an actual "name" for the properties? (ex: Transitive property)