Question

X - 3y = 4
2x - 5y = 8
solve by substitution

Answer 1

x = 4

y = 0

Step-by-step explanation:

Step 1. Pick one equation and rewrite in the form of x= OR y=

x - 3y = 4 (original)

x = 4 + 3y (rewritten)

Step 2. Substitute for x in the other equation

2x -5y = 8 (second equation)

2(4 + 3y) - 5y = 8 (substitute 4 + 3y for x)

Step 3. Solve for the unknown variable, y

2(4 + 3y) - 5y = 8 (distribute)

8 + 6y - 5y = 8 (combine like terms)

y = 0 (first variable)

Step 4. Find x by plugging y into an equation

x - 3y = 4 (original)

x - 3(0) = 4 (substitute 0 for y)

x = 4 (second variable)

FINAL SOLUTION: x = 4, y = 0

You can double check this by plugging these numbers back into each equation; x = 4 and y = 0 is true for both.

I hope this helps!

Answer 2

y = 0

x = 4

Step-by-step explanation:

• x - 3y = 4

• 2x - 5y = 8

make x the subject,

x - 3y = 4

x = 4 + 3y __ equation 1

2x - 5y = 8

x = (8+5y)/2 __ equation 2

using substitution method:

(8+5y)/2 = 4 + 3y

8 + 5y = 8 + 6y

6y - 5y = 8 - 8

y = 0

Find x,

x = 4 + 3y

x = 4 + 3(0)

x = 4