Guadalupe Electric, Inc, must replace a robotic Mig welder and is evaluating two alternatives. Machine A has a fixed cost for the first year of $$50,000$ and a variable cost of $$15,$ with a capacity of $21,000$ units per year. Machine $B$ is slower, with a speed of one$-$half of A$\text{'}$s$,$ but the fixed cost is only $$50,000.$ The variable cost will be higher, at $$19$ per unit. Each unit is expected to sell for $$24.$

a$)$ What is the crossover point $($point of indifference$)$ for the two machines?

The crossover point for the two machines is units. $($Round your response to the nearest whole number.$)$

b$)$ What is the range of units for which machine $A$ is preferable?

Machine $A$ is preferable at a level of production units. $($Enter your response as a whole number.$)$

c$)$ What is the range of units for which machine $B$ is preferable?

Machine $B$ is preferable at a level of production units.$($Enter your response as a whole number.$)$