$y '=\frac{ \mathrm{d} }{ \mathrm{d}x} \left( {\left( 7x-5 \right)}^{4} \right)$
Use the chain rule $\frac{ \mathrm{d} }{ \mathrm{d}x} \left( f\left( g \right) \right)=\frac{ \mathrm{d} }{ \mathrm{d}g} \left( f\left( g \right) \right) \times \frac{ \mathrm{d} }{ \mathrm{d}x} \left( g \right)$, where $g=7x-5$, to find the derivative$y '=\frac{ \mathrm{d} }{ \mathrm{d}g} \left( {g}^{4} \right) \times \frac{ \mathrm{d} }{ \mathrm{d}x} \left( 7x-5 \right)$
Find the derivative$y '=4{g}^{3} \times \frac{ \mathrm{d} }{ \mathrm{d}x} \left( 7x-5 \right)$
Find the derivative of the sum or difference$y '=4{g}^{3} \times 7$
Substitute back $g=7x-5$$y '=4{\left( 7x-5 \right)}^{3} \times 7$
Calculate the product$y '=28{\left( 7x-5 \right)}^{3}$