There are four blue marbles, an unknown number of red (r) marbles, and six yellow marbles in a bag. which expression
represents the probability of randomly selecting a blue marble, replacing it, and then randomly selecting a red marble?
a. 4/10 (r/10)
b. 4/10r ( r/10r)
c. 4/10+r (r/10+r)
d. 4/10 + (r/10r)

The spotter on the ground is standing beneath the safety net. what is his distance from the base of the platform, to the nearest meter? 3 meters, 2 meters, 4 meters, 1 meter?

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling

You need to solve a system of equations. you decide to use the elimination method. which of these is not allowed? 3x - 2y = 7 3x + 4y = 17 equation 1 equation 2