Nathan had 5/6 as many pennies as Ryan. Ryan gave five tenths of his pennies to Nathan and had 50 fewer pennies than his friend. How many pennies did Ryan have at first?
let r = # of pennies ryan has
let n = # of pennies nathan has
n = (5/6)r
r - (5/10)r = n - 50
r - (5/10)r = (5/6)r - 50
.5r = (5/6)r - 50
solve for r, r = 150