Explanation:
we ignore the obvious possibilities of turning one out both tables by 90° to potentially also use their other side lengths.
and we just add the 2 lengths given:
5 ft 11 in + 3 ft 6 in
there are 2 main ways to do that addition :
1. add each size dimension (ft, in) separately, and carry over any "overrun" of dimensional limits from the smaller to the larger unit, if there is one.
2. convert the whole sizes into numbers of the smaller unit.
so, let's try 1 :
5 ft + 3 ft = 8 ft
11 in + 6 in = 17 in
this is an overrun, as 12 in = 1 ft. so, 17 in is 5 in more than 1 ft.
so, we add the additional foot to the 8 ft (8 + 1 = 9 ft) and keep the remaining 5 in on the inches side.
the result :
9 ft 5 in
now, let's try 2.
again, 1 ft = 12 in.
5 ft = 12×5 = 60 in.
3 ft = 12×3 = 36 in.
so, we have
60 in + 11 in + 36 in + 6 in = 113 in
how many ft are in these inches ?
113/12 = 9.41666666...
so, 9 whole ft.
12×9 = 108
so, there are 113 - 108 = 5 in left.
and the result is
9 ft 5 in
so, both tables together are
9 ft 5 in
wide.