<span>Choose two equations and use them to eliminate one variable.Choose another pair of equations and use them to eliminate the same variable.<span>Use the resulting pair of equations from steps 1 and 2 to eliminate one of the two remaining variables.</span></span>
Answer:
Negative controls are particular samples included in the experiment that are treated the same as all the other samples but are not expected to change due to any variable in the experiment.
Step-by-step explanation:
3 tens = 30
Subtract 3 tens from 93
⇒ 93 - 30 = 63
Answer: 63
