a) 5a=N-M/:5
a=N-M/5
b) aX-Y=Z/+Y
aX=Z+Y/:X
a=Z+Y/X
c) U+4a=W/-U
4a=W-U/:4
a=W-U/4
d) Ba-C=D/+C
Ba=D+C/:B
a=D+C/B
e) 5p+ar=3/-5p
ar=3-5p/:r
a=3-5p/r
f) mn-6a=b/+mn
6a=b+mn/:6
a=b+mn/6
g) -3r+2a=1/-(-3)
2a=1-(-3)
2a=4/:2
a=2
