Answer :
Ken will pay $ 871.25 for these items
Explanation
to find the total cost we need add the cost of the blocks to the cost of the total boards, so
Step 1
find the total cost of the blocks
a) when having the cost per unit and the amount, we just need to do a multiplication, so
[tex]\begin{gathered} total\text{ cost= rate*amount} \\ replace \\ tota\text{l cost of the blocks= 7.97}\frac{\text{ \$}}{block}*25\text{ Blocks} \\ tota\text{l cost of the blocks= \$ 199.25} \end{gathered}[/tex]Step 2
now, the total cost of the boards:
[tex]\begin{gathered} total\text{ cost= rate*amount} \\ replace \\ tota\text{l cost of the boards= 14}\frac{\text{ \$}}{board}*4\text{8 boards} \\ tota\text{l cost of the boards= \$ 672} \end{gathered}[/tex]Step 3
finally, add the costs to find the total
[tex]\begin{gathered} total\text{ cost= \$199.25+672} \\ total\text{ cost= 871.25} \end{gathered}[/tex]therefore, Ken will pay $ 871.25 for these items
I hope this helps you