The answer would be 3. {0,3}.
Remember: {x,y}
2(0)+3=3
0+3=3
0+3=3
Triple w is just 3w, so v times that is just 3vw
Children=x
Adults=y
* x + y =275 => x = 275 - y
* 3.00x + 6.40y = 1284 <=> 3.00(275 - y) + 6.40y = 1284 <=> ... <=> y = 135 => x = 275 - 135 = 140
Children: 140
Adults: 135
I don't know if this is the right one but i hope this helps. this is how i learned it.
step 1=get variables on one side oof the equal sign by using inverse operation (add or subtract smaller variable)
step 2= get constants away from variable to the other side of the equal sign by using inverse operations (add or subtract constant)
step 3: isolate the variable using inverse operation (multiply or divide)