Question 1160518
change in 50 years is $54600 in Pa and $107,700 in NJ

slope is 1092 in PA, increase in $1092 every year
slope is 2154 in NJ, increase in $2154 every year 

in another 10 years the home price would increase $1092*10 or $10,920 in PA and the price would be the added to $97000 or $107920.

x years prior to 1950 the price in PA was 42400-1092x and in NJ 63100-2154x
Set those two equal
20700=1062x
x=19.49 years  or in mid-1930.

another way is to look at the difference in prices in 1950, which is $20700 and the difference in growth, which is $1062. Divide the two numbers.