Question 356607
Let r = speed of roberto, j = speed of juana.  Using the formula D = RT, (distance = rate x time),  the 1st and 2nd sentences give
{{{6r = 30 + 6j}}}.  The 3rd sentence implies that {{{1r + 1j = 30}}}.
The first equation is the same as {{{r -j = 5}}}, after transposition and dividing both sides by 6.  The 2nd equation is just {{{r+j=30}}}.  Adding corresponding sides of these 2 equations, we get {{{2r = 35}}}, or r = 17.5 miles per hour.  Then j=30 - r = 12.5 miles per hour.