Step-by-step explanation:
Since we have given that
Amount of pay rate =$21
If she marked up by 78.7% , so it becomes
[tex]78.7\%\text{ of}\$21\\\\=\frac{78.7}{100}\times \$21\\\\=\$16.527[/tex]
So, our amount for pay rate becomes
[tex]21+16.527\\\\=\$37.527[/tex]
Now, he said he made a profit of 10%,so it becomes
[tex]10\%\text{ of }37.527\\\\=\frac{10}{100}\times 32.527\\\\=\$3.7527[/tex]
So, our new pay rate becomes
[tex]37.527+3.7527\\\\=\$41.2797[/tex]
This is the step through which we can get $41.28.