Answer: The required number of apples altogether is 240.
Step-by-step explanation: Given that there were 20 more apples in basket A than in basket B.
Mr. Bell transferred 50 apples from basket b to basket A. There were 3 times as many apples in basket A as in basket B.
We are to find the total number of apples.
Let x and y represents the number of apples in bags A and B respectively.
Then, according to the given information, we have

and
![x+50=3(y-50)\\\\\Rightarrow y+20+50=3y-150~~~~~~~~~~~~~~~~~~~~~~[\textup{using equation (i)}]\\\\\Rightarrow y+70=3y-150\\\\\Rightrarow 3y-y=70+150\\\\\Rightarrow 2y=220\\\\\Rightarrow y=(220)/(2)\\\\\Rightarrow y=110.](https://img.qammunity.org/2020/formulas/mathematics/high-school/3iez2en5gaffl97dzamodc2ggkyz6irfk1.png)
From equation (i), we get

Therefore, the total number of apples is given by

Thus, the required number of apples altogether is 240.