7th Grade Math
Please help
-7 = 1/3 a
Find the value of a

Weekly wages at a certain factory are normally distributed with a mean of $400 and a standard deviation of $50. find the probability that a worker selected at random makes between $450 and $500

Select all expressions that are equivalent to 2(3x + 7y). question 1 options: 6x + 14y 6x + 7y 1(6x + 14y)

Out of 50 students surveyed, 16 have a dog. based on these results, predict how many of the 280 students in the school have a dog.