Answer: 14 red, 7 green, 44 blue
Explanation:
First, use the letter r as a variable to represent the number of red Legos. The number of green Legos (g) is 7 less than the number of red Legos, or g = r-7. The number of blue Legos (b) is 2 more than 3 times the number of red Legos, or b = 3r+2. The total number of Legos is the number of red + green + blue Legos, which can be represented as 65 = r+g+b.
Substitute the equations for g and b in. This should give you a final equation of 65 = r+(r-7)+(3r+2). To solve for the number of red Legos, first add up all of the terms to get 65 = 5r-5. Now add 5 to each side (70 = 5r). Finally, divide each side by 5 (r = 14).
To find the number of green Legos, substitute the number of red Legos (14) into the equation for the green Legos (g = r-7). This should get you the equation g = 14-7 which simplifies to g = 7.
To find the number of blue Legos, substitute the number of red Legos (14) into the equation for the blue Legos (b = 3r+2). This gives you the equation b = (3*14)+2. First, multiply 3 and 14 to get b = 42+2. Finally, add them together to get b = 44.