Please consider looking over the steps I provide to enlighten your understanding on the concept. Thank you.
21.
change the mixed fractions to improper ones:
3 1/5=
3*5=15+1
16/5
7 1/2=
7*2=14+1=15
15/2
Now we have the fractions 16/5 and 15/2, so convert these to decimals:
16/5=3.2
15/2=7.5
refine the equation:
p+3.2=7.5
subtract:
p+3.2-3.2=7.5-3.2
p=4.3
convert 4.3 to a fraction:
4.3=
4 3/10
21. Thus, p=4 3/10
23.
n-0.36=4.8
add:
n-0.36+0.36=4.8+0.36
n=5.16