Solve the equation: 21 − 3(x − 7) = x + 20
Answers
21 – 3 (x – 7) = x + 20
☁⇒ 21 – 3x + 21 = x + 20 ⇒ 42 – 3x = x + 20
☁⇒ 42 – 20 = x + 3x ⇒ 4x = 22
☁⇒ x = 22/4 = 11/2 = 5.1/2
☁∴ x = 5.1/2
Distribute
2
1
−
3
(
−
7
)
=
+
2
0
21{\color{#c92786}{-3(x-7)}}=x+20
21−3(x−7)=x+20
2
1
−
3
+
2
1
=
+
2
0
21{\color{#c92786}{-3x+21}}=x+20
21−3x+21=x+20
2
Add the numbers
2
1
−
3
+
2
1
=
+
2
0
{\color{#c92786}{21}}-3x+{\color{#c92786}{21}}=x+20
21−3x+21=x+20
4
2
−
3
=
+
2
0
{\color{#c92786}{42}}-3x=x+20
42−3x=x+20
3
Rearrange terms
4
2
−
3
=
+
2
0
{\color{#c92786}{42-3x}}=x+20
42−3x=x+20
−
3
+
4
2
=
+
2
0
{\color{#c92786}{-3x+42}}=x+20
−3x+42=x+20
4
Subtract
4
2
42
42
from both sides of the equation
−
3
+
4
2
=
+
2
0
-3x+42=x+20
−3x+42=x+20
−
3
+
4
2
−
4
2
=
+
2
0
−
4
2
-3x+42{\color{#c92786}{-42}}=x+20{\color{#c92786}{-42}}
−3x+42−42=x+20−42
5
Simplify
Subtract the numbers
Subtract the numbers
again
−
3
=
−
2
2
-3x=x-22
−3x=x−22
x = 11/2
ʜᴏᴩᴇ ɪᴛ' ʜᴇʟᴩ ᴜʜʜ