Answer:
2a²+4b²
Step-by-step explanation:
first distribute the ^2 into the parenthesis for each
7a²+2b²-2a²+7b²all over 4a²+b²-a²+4b²
now combine like terms
5a²+9b² all over 3a²+5b²
now cancel out 9b²-5b²=4b²
5a²-3a²=2a²