## Algebra 1: Common Core (15th Edition)

Step 1: We make the assumption that 90 is 100% since it is our output value. Step 2: We next represent the value we seek with $x$. Step 3: From step 1, it follows that $100\%=90$. Step 4: In the same vein, $x\%=54$. Step 5: This gives us a pair of simple equations: $100\%=90(1)$. $x\%=54(2)$. Step 6: By simply dividing equation 1 by equation 2 and taking note of the fact that both the LHS (left hand side) of both equations have the same unit (%); we have $\frac{100\%}{x\%}=\frac{90}{54}$ Step 7: Taking the inverse (or reciprocal) of both sides yields $\frac{x\%}{100\%}=\frac{54}{90}$ $\Rightarrow x=60\%$ Therefore, $54$ is $60\%$ of $90$.