Question

Descubra o valor de a:
a) a+4a+20=90
b)a/2+a+12=90
c) a+40+2a/3=90
d)a/4+20a+40=90

Answer 1

a)
$a + 4a + 20 = 9 = \\ 5a = 90 - 20 = \\ 5a = 70 = \\ a = \frac{70}{5} = 14$
b)
$\frac{a}{2} + a + 12 = 90 = \\ \frac{a}{2} + a = 90 - 12 = \\ \frac{2a}{2} = 78 = \\ a = 78$
c)
$a + 40 + \frac{2a}{3} = 90 = \\ a + \frac{2a}{3} = 90 - 40 = \\ 3a = 50 = \\ a = \frac{50}{3} = 16.66...$