2x + 3y = 630
x + y = 245 then you want to get rid of x so in the second equation × by -2 and get -2x -2y =-490 subtract this equation from the first to get y=$140 substitute 140 in for y and get x= $105 and 2x=210 and 3y=420 210 +420=630
The answer is -2y•(2y^4 - 3y^2 - 4y + 1)
Problem: 2/7 (4+c)=6
1. 7/2 x 2/7 x (4+c)=7/2 x 6
2. 4+c=7 x 3
3. 4+c=21
4. c=21-4
Answer: c=17
Ok so, 15 of them know how to play whist (I have no idea what that is) and 20 of them know how to play dominoes, 5 of them do not. So, if you add up 20+15=35, take off 10 35-10=25 so it must mean that 10 is the answer. (Also if you add 5 to that 25+5=30)
The Answer is 10
They went there in 6.5 hours and came back in 5.8 hours