a) $\frac{42\times 45}{5\times 7}$ = $\frac{6\times \not{7}\times \not{5}\times 9}{\not{5}\times \not{7}}$ = 54
b) $\frac{54\times 56}{7\times 9}$ = $\frac{6\times \not{9}\times \not{7}\times 8}{\not{7}\times \not{9}}$ = 48
a) $\frac{42\times 45}{5\times 7}$ = $\frac{6\times \not{7}\times \not{5}\times 9}{\not{5}\times \not{7}}$ = 54
b) $\frac{54\times 56}{7\times 9}$ = $\frac{6\times \not{9}\times \not{7}\times 8}{\not{7}\times \not{9}}$ = 48