Question 617585
Write an equation for each statement:
:
Anne and Ben have the total weight of 120 kilograms. 
a + b = 120
b = (120-a)
:
Ben and Charlie have the total weight of 130 kilograms.
b + c = 130
Replace b with 120-a
120-a + c = 130
-a + c = 130 - 120
-a + c = 10
c - 10 = a
:
 Anne and Charlie have the total weight of 150 kilograms.
a + c = 150
replace a with (c-10)
(c-10) + c = 150
2c = 150 + 10
2c = 160
c = 160/2
c = 80 kg is Charlie's weight