Mr. Francis bought a pair of shoes on sale for 40% off. The regular price was $55, not including tax. How much did Mr. Francis p
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Answer:
Step-by-step explanation:
When they ask you to make a variable the "subject of the formula", they're basically asking you to build a "machine" for it. In the expression , for instance, if we know what m, x, and b are, we can plug them all in and out comes a value for y! To build that machine, we need to get it by itself on one side of the equation.
So, we want to build this machine for p, and the equation we have to build it out of is
One think we can immediately say about this equation: for a fraction to be equal to one, its numerator and denominator have to be equal to each other. So we can say
Ok, what next? Well, if we want p by itself, we need to somehow peel it off of that <em>sp</em> and <em>pk</em>. Let's collect them on the right side by subtracting <em>sp </em>from both sides:
p is a <em>common factor</em> of both <em>sp </em>and <em>pk</em>, so we can peel it away using the distributive property:
And from here, we can divide both sides by and we'll have p as our subject:
or
So if we know m, k, and s, we can easily solve for p. If m = 4, k = 2, and s = 0:
