Question

determine a e b sabendo que:a)a+b=55 e a/b=4/7 b)a+b=91 e 4/9=a/b

Answer 1

a)
a+b = 55
a = 55-b

a/b = 4/7
(55-b)/b = 4/7
4b = 7(55-b)
4b = 385 -7b
4b + 7b = 385
11b = 385
b = 385/11
b = 35
a = 55-b
a = 55-35
a = 20


b)
a+b = 91
a = 91-b

4/9 = a/b
4/9 = 91-b/b
4b = 9(91-b)
4b = 819 - 9b
4b + 9b = 819
13b = 819
b = 819/13
b = 63
a = 91-b
a = 91-63
a = 28