Answer:
a +b -3c +15
Step-by-step explanation:
Write the subtraction you want to perform, use the distributive property, collect terms:
(3a-4b-c+6) -(2a-5b+2c-9)
= 3a -4b -c +6 -2a +5b -2c +9 . . . . . . distribute the minus sign
= a(3-2) +b(-4+5) +c(-1-2) +(6+9) . . . . find and group like terms
= a +b -3c +15
