Imagine Becca as x, Al as 2x (Since he is twice as tall), and Jim as 2x+3 (since he is 3 inches taller than Al). Then make an equation out of their values and set it equal to 199.
x+(2x)+(2x+3)=199
5x+3=199
5x=196
x=39.2
Now we know that Becca is 39.2 inches so now plug in 39.2 for x in Jim's number.
2x+3
2(39.2)+3
78.4+3
81.4
Jim is 81.4 inches tall
