$$7\times 3^{0}\times 4^{\frac{3}{2}}$$
Calculate $3$ to the power of $0$ and get $1$.$$7\times 1\times 4^{\frac{3}{2}}$$
Multiply $7$ and $1$ to get $7$.$$7\times 4^{\frac{3}{2}}$$
Calculate $4$ to the power of $\frac{3}{2}$ and get $8$.$$7\times 8$$
Multiply $7$ and $8$ to get $56$.$$56$$