X + 3x = 12
(Or 4x=12)
the first x is the number of girls then the second x is the girls times 3, which is how many boys there are.

solve for "a", to see what Africa's population will then be
9x +5y= -45
put in standard form
y= mx+b
coefficient of x is the slope, b is the y intercpept
5y= -9x -45
y= -9/5 x -45
graphing will start at -45 on the y axis
from that point go down 9 to the right 5 for the slope continue and graph minimum
2 points to draw the line
hope this helps
Answer:
for number 1, you plug -3 in for x in the equation. and for number 2, you plug in 2 for y in the equation. you do this to find the missing values of the variables.
1. y= -10
2. x= -1
Step-by-step explanation:
i hope this helps :)