Let x be the number of pens in a box.
Jill : three full boxes of pen and 2 loose pens. 3x + 2
Ben: two full boxes of pen and 14 loose pens. 2x + 14
Jill and Ben have the same pens.
Jill = Ben
3x+2 = 2x + 14
3x - 2x = 14 - 2
1x = 12
x = 12
To check:
Jill = Ben
3x + 2 = 2(x) + 14
3(12) + 2 = 2(12) + 14
36 + 2 = 24 + 14
38 = 38
There are 12 pens or a dozen of pens in a full box.
keeping in mind that parallel lines have exactly the same slope, let's check for the slope of the equation above

so we're really looking for the equation of a line whose slope is 1/2 and passes through (-4 , 1)

1,000,000,000 standard form
one billion word form
Speed of the waves because a wave can get faster