one way to find out is o factor
70=7 times 10
90=7 times 10
remember that [tex] \frac{x}{y} times \frac{z}{t} [/tex]=[tex] \frac{x times z}{y times t} [/tex] so
70/90=7/9 times 10/10=7/9 times 1=7/9
any fraction that is multiplied by 1 or x/x remains the same value so some examples of equivilent fractions are
7/9 times 2/2=14/18
7/9 times 3/3=21/27
etc
