Answer:
64 or more
Step-by-step explanation:
First, find the average of three tests scores:
[tex]\dfrac{69+88+73}{3}=\dfrac{230}{3}\approx 77[/tex]
Now
77 points - 40%
63 points - 20%
69 points - 20%
x points - 20%
Overall score must be 70 or better, so
[tex]0.4\cdot 77+0.2\cdot 63+0.2\cdot 69+0.2\cdot x\ge 70\\ \\30.8+12.6+13.8+0.2x\ge 70\\ \\57.2+0.2x\ge 70\\ \\0.2x\ge 70-57.2\\ \\0.2x\ge 12.8\\ \\2x\ge 128\\ \\x\ge 64[/tex]