Givens
x + y = 3
x =6 - 4y
Solution
Use the top equation to substitute for x in the second equation.
x = 3 - y
Put this result into the second given equation and solve for y
3 - y = 6 - 4y Add 4y to both sides.
3 - y + 4y = 6 Combine on the left
3 + 3y = 6 Subtract 3 from both sides
3 - 3 + 3y = 6 - 3 Combine
3y = 3 Divide by 3
3y/3 = 3/3 Combine
y = 1
=========================
x + y = 3 but y = 1
x + 1 = 3 Subtract 1 from both sides.
x + 1 - 1 =3 - 1
x = 2
Answer
x = 2
y = 1
0.7/1 of a wall per person
Answer:
a. Let the variable be
for the fundraising activities and
as the revenue for foundation.
b. 
c. $43.2
d. $1416.67
Step-by-step explanation:
Given that:
The World Issues club donates 60% of the total of their fundraising activities.
Answer a.
Let us choose the variable
to represent the money earned during fundraising activities and
for the revenue generated for foundation.
Answer b.
Foundation will receive 60% of the total of the fundraising activities.
Equation to determine the money that will be received by foundation:

Answer c.
Given that x = $72, M = ?
Putting the value of x in the equation above:

Answer d.
Given that M = $850, x = ?
Putting the value of M in the equation above to find x:

So, the answers are:
a. Let the variable be
for the fundraising activities and
as the revenue for foundation.
b. 
c. $43.2
d. $1416.67
Rewrite 5% as a decimal and then multiply by 60.
X = 0.05 x 60