You divide 18 with 3 and is going to equal 6 so that should be your constant proportionality
Subtract 4x from both sides
Then divide both sides by 9 to isolate y
Y=(6-4x)/9
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To find the product of a reasonable estimate of two decimal numbers, round each decimals to the nearest whole number and then perform the multiplication.
For example:
3.2 x 5.7
Estimated answer
3.2 will be rounded down to 3 and 5.7 will be rounded up to 6
⇒ 3 x 6 = 18
Actual Answer
3.2 x 5.7
=18.24
