Algebra Solve by Substitution

six times the number of girls
Let g = number of girls

• 6 + g

• 6g

• g - 6

Define substitute.

• the number multiplied by a variable

• to replace a variable with a value or an expression

• a number standing alone

• to find the value of an expression

if x = 4,

calculate 2x + 5

• 9

• 13

• 13x

• 8x + 5

let x = 4 and y = 7,

Calculate x + 2y

• 15

• 4 + 14y

• 18

• x + 14

Solve this system by substitution.

• (1, -4)

• (1, 4)

• (-4, -7)

• (-7, -4)

Find the value of (x, y) that satisfies the equations by solving the system using substitution.
 
5x + 4y= −14
y =  −7x  −  15  The solution is (a)   .

• (-2, -1)

• (0, 0)

• (1, 1)

• (2, 2)

The solution to the system of equations x + 2y = 2 and x = -4y + 2 is (a)   .

• (2, 0)

• (0, 2)

• (1, 1)

• (-2, 2)

take 10 away from s 

• 10 - s 

• s + 10

• s - 10

• s/10

let x = 6 and y = 3,

calculate 3x - 4y

• 18x - 12y

• 6(x - y)

• 12

• 6

Which equation shows the correct first step to solve the system by substitution

• 2=4x-2

• 2x-8y=4x-2

• 2x-8(4x-2)=2

• 2(4x-2)-8y=2