Question

Calvulati nr x stiind ca a-b=6

a)x•a-x•b+9a-9b=654
b)7•a-7•b+x=55
c)13+x-(5•a-5•b)=2011

Answer 1

a)   x · a - x · b + 9 a - 9 b = 654

x ( a - b ) + 9 ( a - b ) = 654

( a - b ) ( x + 9 ) = 654

6 ( x + 9 ) = 654

6 x + 54 = 654

6 x = 654 - 54

x = 600 : 6  ⇒   x = 100

___________________

b)   7 a - 7 b + x = 55

7 ( a - b ) + x = 55

7 × 6 + x = 55

42 + x = 55

x = 55 - 42

x = 13

________

c)   13 + x - 5 ( a - b ) = 2011

13 + x - 5 × 6 = 2011

13 + x - 30 = 2011

x = 2011 + 30 - 13

x = 2041 - 13

x = 2028