Start by calling the unknown amount 'x'. We can then set up a relationship to represent the question:
\(213 = (30\%) \times x\)
or
\(213=0.3x\)
and then solve for x, by dividing both sides of our equation by 0.3
\(\frac{213}{0.3}=\frac{0.3x}{0.3}\)
\(710=x\)
213 is 30% of 710
To check: \(710 \times 0.3 = 213\)
