2x+y=0 ×-y=6 what is the solution to this system of equations?

1. if we have 3 babies what is the probability they’re going to be all boys? 2. if we roll 2 die at the same time what is the probability of getting less than 10 on the first roll and a 5 on the second roll 3. if we have 3 babies what is the probability their is going to be 2 girls? 4. if we have 3 babies what is the probability of having no more than 1 girl? 5. it we have 3 babies and then have another 3 babies what is the probability of us having at least 1 boy and then having all girls?

Standard deviation of 19,29,21,22,23

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'