human
Simplify algebraic expressions to maintain equivalence by collecting like terms involving just two linear variables Which expression should replace the star in the addition pyramid? ![A pyramid showing the expressions 2a, -b and 2a-2b across the base from left to right. Above the 2a and -b is a star. Above the -b and the 2a-2b is written 2a-3b]() \( -2 a b \)
gpt
Multiplies rather than adds 