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Sometimes there are problems that need slightly more complicated equations.
For example, let's say you want to buy a coat that costs $100. You
have $40. Your mum has told you that she will match whatever amount
of money you can save to help you buy the coat. How much do you need
to save?
| Amount you need to save |
let's call it 'n' |
| Amount you'll have after you have saved
and your mum has matched (or doubled) it. |
2 x n (or 2n)
|
| Amount you already have |
40 |
| Amount you need |
100 |
| Putting it altogether |
2n + 40 = 100 |
To solve equations like 2n + 40 = 100 we need to "get rid of" two things:
the +40 and the x2. We need to do two things and
the order we do them in is important. The examples below show
what we can do to solve these types of equations:
|
| Step 1: Subtract 40 from both sides |
2n + 40 - 40 =
100 - 40 |
| |
2n = 60 |
| Step 2: Divide both sides by 2 |
2n ÷ 2 = 60 ÷ 2 |
| |
n = 30 |
It is very important that we solve equations like the ones on this
page by doing the addition or subtraction before doing the division
or multiplication.
|
| Step 1: Add 7 to both sides |
3n - 7 + 7 =
17 + 7 |
| |
3n = 24 |
| Step 2: Divide both sides by 3 |
3n ÷ 3 = 24 ÷ 3 |
| |
n = 8 |
|
| Step 1: Subtract 8 from both sides |
|
| |
|
| Step 2: Multiply both sides by 7 |
|
| |
a = 7 |
|
| Step 1: Add 16 to both sides |
|
| |
|
| Step 2: Multiply both sides by 2 |
|
| |
b = 112 |
Print the worksheets below to help practice solving equations using
two steps.
The four worksheets above are also included here
with more solving equations worksheets.
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Solving
equations in two steps (1 of 4)