Answer:
10·b = 60
Explanation:
The given system of equation is presented as follows;
5·a + 5·b = 25...(1)
-5·a + 5·b = 35...(2)
Given that the coefficient of a in equation (1) is equal in magnitude but opposite in sign to the coefficient of 'a' in equation (2), to eliminate the variable 'a' when using the elimination method, we add both equations as follows;
5·a + 5·b + (-5·a + 5·b) = 25 + 35 = 60
5·a - 5·a + 5·b + 5·b = 60
5·a - 5·a = 0
5·b + 5·b = 10·b
∴ 5·a - 5·a + 5·b + 5·b = 60 = 0 + 10·b = 10·b
∴ 10·b = 60