Answer :
t=tables
b=booths
t+b=27
8t+4b=140
solve
8t+4b
divide both sides by 4
2t+b=35
we have
t+b=27
2t+b=35
it should be obvious that the answer is 8 but using math
multipl first eqution by -1 and add to second
-t-b=-27
2t+b=35 +
1t+0b=8
t=8
sub
t+b=27
8+b=27
minus 8 both sides
b=19
19 booths
b=booths
t+b=27
8t+4b=140
solve
8t+4b
divide both sides by 4
2t+b=35
we have
t+b=27
2t+b=35
it should be obvious that the answer is 8 but using math
multipl first eqution by -1 and add to second
-t-b=-27
2t+b=35 +
1t+0b=8
t=8
sub
t+b=27
8+b=27
minus 8 both sides
b=19
19 booths
t + b = 27.......t = 27 - b
8t + 4b = 140
8(27 - b) + 4b = 140
216 -8b + 4b = 140
-8b + 4b = 140 - 216
-4b = -76
b = -76/-4
b = 19....19 booths
8t + 4b = 140
8(27 - b) + 4b = 140
216 -8b + 4b = 140
-8b + 4b = 140 - 216
-4b = -76
b = -76/-4
b = 19....19 booths