Your mother gave you $13.32 with which to buy a present. This covered 3/5 of the cost. How do you write and solve as an equation to find how much the present cost?

2 Answers
Alan P.
Oct 29, 2016

The present cost #$22.20#

Explanation:

Represent the cost of the present by the variable #color(blue)(c)#

We are told
#color(white)("XXX")color(red)(3/5 xx color(blue)(c) =$13.32)#
(this is the requested equation)

Multiplying both sides by #5/3# (to get rid of the fraction on the right side)
#color(white)("XXX")cancel(5)/cancel(3) xx cancel(3)/cancel(5) xx color(blue)(c)=(cancel($13.32)^($4.44) xx 5)/cancel(3)#

#color(white)("XXX")rarr color(blue)(c)= $22.20#

Shell
Oct 29, 2016

The cost of the present is #$22.20#.

Explanation:

The question can be restated as:

#3/5#th of the cost is #13.32#.

When "translating" words to an equation, "of" means multiplication and "is" means equal.

Let #x=# the cost.

#3/5 x = 13.32#

Multiply both sides by #5/3#

#5/3 * 3/5 x = 5/3 * 13.32#

#cancel5/cancel3 * cancel3/cancel5 x = (5*13.32)/3#

#x=22.2#, so the cost of the present is #$22.20#.

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