填一填.
70+70+70+70= × =
51×4= × + × = + =
700+700+700= × =
3×400= + + =
× =90+90+90+90= .
填一填.
70+70+70+70= × =
51×4= × + × = + =
700+700+700= × =
3×400= + + =
× =90+90+90+90= .