How do you solve by substitution #a = 3b - 4# and #a + b =16#?

2 Answers
Apr 2, 2018

Answer:

#b=5#
#a=11#

Explanation:

#a=3b-4# ----(1)
#a+b=16#----(2)

From (2),
#a=16-b# ----(3)

Sub (3) into (1)
#16-b=3b-4#
#20 = 4b#
#b=5#
#a=11#

Apr 2, 2018

Answer:

#a=11# and #b=5#

Explanation:

We know a in terms of b with the help of equation 1 #a=3b-4#

So put that that in equation 2,
#3b-4+b=16#
Add 4 on both sides
#4b=20#
Divide both sides by 4
#b=5#

Substitute that in one of the original equations

#a+5=16#
Subtract 5 from both sides
#a=11#

So #a=11# and #b=5#