Please help me I’ve been struggling.

With #! i’ve tried to figure it out but i can’t.

Look at arnold's attempt to solve the equation for b: 3b = 12 b = 3 · 12 b = 36 describe the mistake that arnold made.

Campus rentals rents 2 and 3 bedrooms apartments for $700 ans $900 a month respectively. last month they had six vacant apartments and reported $4600 in lost rent. how many of each type of apartment were vacant?