Xavier, Thomas, and Mei had 650 marbles. Thomas had 3 times as many marbles as Mei. Mei had 50 fewer marbles than Xavier. How many marbles did Xavier and Mei have altogether? *

230 Marbles

Step-by-step explanation:

Let Xavier marbles be x

Let Thomas marbles be y

Let Mei marbles be z

Xavier, Thomas, and Mei had 650 marbles.

x + y + z = 650

Thomas had 3 times as many marbles as Mei.

y = 3 × z

y = 3z

Mei had 50 fewer marbles than Xavier.

x = z - 50

We can plug all the equation gotten back into the first equation

x + y + z = 650

Since y = 3z and x = z - 50

x + y + z = 650

(z - 50) + 3z + z = 650

z - 50 + 3z + z = 650

5z - 50 = 650

5z = 650 + 50

5z = 700

z = 700/5

z = 140

Mei has 140 marbles

Since x = z - 50

x = 140 - 50

x = 90

Xavier has 90 marbles

y = 3z

y = 3 × 140

y = 420

Thomas has 420 marbles

Xavier and Mei marbles = 90 + 140

= 230 marbles