2
$(20 + 10) + 30 =$
$20 + (10 + 30) =$
$(15 + 25) + 35 =$
$15 + (25 + 35) =$
$(43 + 39) + 61 =$
$43 + (39 + 61) =$
$(87 + 46) + 54 =$
$87 + (46 + 54) =$
$(95 + 84) + 16 =$
$95 + (84 + 16) =$
$(77 + 46) + 54 =$
$77 + (46 + 54) =$
$(63 + 48) + 52 =$
$63 + (48 + 52) =$
$(96 + 73) + 27 =$
$96 + (73 + 27) =$
$(54 + 76) + 24 =$
$54 + (76 + 24) =$
$(37 + 63) + 38 =$

$(20 + 10) + 30 = 30 + 30 = 60$
$20 + (10 + 30) = 20 + 40 = 60$
$(15 + 25) + 35 = 40 + 35 = 75$
$15 + (25 + 35) = 15 + 60 = 75$
$(43 + 39) + 61 = 82 + 61 = 143$
$43 + (39 + 61) = 43 + 100 = 143$
$(87 + 46) + 54 = 133 + 54 = 187$
$87 + (46 + 54) = 87 + 100 = 187$
$(95 + 84) + 16 = 179 + 16 = 195$
$95 + (84 + 16) = 95 + 100 = 195$
$(77 + 46) + 54 = 123 + 54 = 177$
$77 + (46 + 54) = 77 + 100 = 177$
$(63 + 48) + 52 = 111 + 52 = 163$
$63 + (48 + 52) = 63 + 100 = 163$
$(96 + 73) + 27 = 169 + 27 = 196$
$96 + (73 + 27) = 96 + 100 = 196$
$(54 + 76) + 24 = 130 + 24 = 154$
$54 + (76 + 24) = 54 + 100 = 154$
$(37 + 63) + 38 = 100 + 38 = 138$