Question

Stiind ca x=14,calculati a+b in fiecare din cazurile

c)39*a+39*b-39*x=3900
d)x*a+x*b=140
g)9*x-2a-2*b=100
h)x*a+x*b+6*a+6*b=200

Answer 1

c) 39*a + 39*b - 39*x=3900

39(a+b-x) =3900 | : 39

a+b-x = 100

a+b- 14 = 100 | +14

a + b = 114

d) x*a+x*b=140

x(a+b)=140

14 (a+b) = 140 | : 14

a + b = 10

g) 9*x-2a-2*b = 100

9 * 14 - 2a - 2*b = 100

126 - 2a - 2*b = 100

126 - 100 = 2a + 2 * b

26 = 2(a+b) => a+b = 13

h) x*a+x*b+6*a+6*b = 200

x(a+b) + 6( a+b) = 200

14 (a+b) + 6( a+b) = 200

20 ( a+b) =200 | : 20

a+b = 10