3k+10=2k-21
move 2k to the other side
sign changes from +2k to -2k
3k-2k+10=2k-2k-21( combine like terms)
3k-2k+10= -21
k+10=-21
move +10 to the other side
k+10-10= -21-10
k= -21-10
answer:
k= -31
