Can someone freaking tell me how to multiply using expanded form

It has to do with the place value of ur numbers...
Lets say ur problem is 342 x 6

the 3, which is in the hundreds place becomes 300
the 4, which is in the tens place becomes 30
the 2 , which is in the ones place becomes 2

multiplied by 6...
300 x 6 = 1800
40 x 6 = 240
2 x 6 = 12

so, 342 x 6 = 1800 + 240 + 12 = 2052

another example :
1042 x 4 =

1000 x 4 = 4000
0 x 100 = 0
40 x 4 = 160
2 x 4 = 8

so, 1042 x 4 = 4000 + 0 + 160 + 8 = 4168

The answer is: y would equal 3 because if you simplify the equation then it would be y= 3x+9 and if you divide 3x and 9 by 3 it would equal 3. y= 3