How many different ways can the letters of statistics be arranged

Find an equation for the linear function which has slope -10 and x-intercept -7

Avery’s piggy bank has 300 nickels, 450 pennies, and 150 dimes. she randomly picks three coins. each time she picks a coin, she makes a note of it and puts it back into the piggy bank before picking the next coin.

Which shows the first equation written in slope-intercept form? 1/2 (2y + 10) = 7x